A. P. Sinnett had written to a master (in letter 23A) a number of questions. Here is question 4:
(4) To what epoch did the existence of the Continent of Atlantis belong, and did the cataclysmical change which produced its extinction come into any appointed place in the evolution of the round, — corresponding to the place occupied in the whole manvantaric evolution by obscurations?
He got back this answer in letter 23b:
"It [science] now teaches, as you know, that Atlantis, or the remnants of it lingered down to post-tertiary times, its final submergence occurring within the palaeozoic ages of American history! Well, truth and fact ought to feel thankful even for such small favours in the previous absence of any, for so many centuries. The deep sea explorations — especially those of the Challenger, have fully confirmed the reports of geology and palaeontology. The great event — the triumph of our “Sons of the Fire Mist,” the inhabitants of “Shamballah” (when yet an island in the Central Asian Sea) over the selfish but not entirely wicked magicians of Poseidonis occurred just 11,446 ago."
As far as I know this is the only instance of an exact year for the sinking of Atlantis given anywhere. If anyone else knows of an exact year asserted or presumed from any source for this event please let me know.
Now we need to translate "11,446 years ago" into an exact year. The letter from the master was written in October of 1882. There are some indications from myths that the event occurred in the spring and other indications that it occurred in the summer. (Some few myths give this indication of a month but none give an indication of a year.) So if we assume it occurred in the 9 to 10 months of the year prior to the writing of the master's letter, and if we note that the year "0" never occurred, then this translates into the year 9,565 BC.
In the Secret Doctrine, HPB has more than once indicated 12,000 years ago. Of course these two dates are compatible with the master's date being more specific.
So, Theosophy has an asserted year for the sinking of Atlantis and that year is 9,565 BC.
Now it happens that the book Cataclysm has calculated a proposed year along with a range for its estimate of the date of the event. It averages together 574 separate carbon fourteen dates to come to a grand average of 11,577 BP. (BP means "before present" and is defined as before January 1, 1950. It is used by scientists to eliminate "Christ" from the dating terminology - even though a "BC" factor entered into the definition of the term.) This translates to 9,628 BC, or only 63 years away from Theosophy's date.
To form their best estimate, the authors of Cataclysm then decide to round their BP date from 11,577 to 11,500 BP and offer a range of plus or minus 50 years. This new estimate of 11,577 BP translates into 9,551 BC. This new date is only 14 years away from Theosophy's date of 9,565 BC. This is astounding!
Let's put it simply. When science has averaged together 574 radiocarbon dates and then picked a slightly yet rounder number for its estimate of this event, it then comes to only 14 years from the date asserted by Theosophy in the year 1888!!
Can we say Theosophy has been confirmed?
And yet a little more. Since Cataclysm gives a range of plus or minus 50 years, Theosophy's date is well within this estimated range from science.
Okay, I'll say it. Theosophy's dating of the sinking of Atlantis has been confirmed. This is an extraordinary match that Theosophists should be aware of. We each need to evaluate the extent to which this vindicates the knowledge of Theosophy about Atlantis. When we consider how strongly science has objected to the reality of Atlantis then it gives all the more significance to this vindication - and all the more weight to the Secret Doctrine.
There is one more detail that is subject to interpretation. Sinnett asked the master about the "cataclysmical extinction" of Atlantis. The master did not reply "Atlantis sunk in year XX." Instead the master said "the great event occurred ...". It appears to me the master knew that much more had occurred than that an island had sunk. It appears to me that he knew a "great event" had occurred. It was more than the extinction of an island. And that would be much more in keeping with this analysis.